Sealing device



July 22, 1941. A. HOLLANDER ETAL 2,249,763

' SEALING DEVICE I Filed Dec. 8, 1937 2 Sheets-Sheet 2 -l 1'" Hm IllPatented July 22, 1941 SEALING DEVICE Aladar Hollander and Vaino A.Hoover, Los Angeles, Calif., assignors-to Byron Jackson 00., HuntingtonPark, Calif., a corporation of Delaware Application December 8, 1937,Serial No. 178,739

13 Claims. (01. 286-9) This invention relates to a sealing device, andmore particularly to a liquid seal adapted to seal the juncture of arotating shaft and a stationary member. f

The invention has particular utility in sealing the juncture of thedrive shaft of a submersible electric motor and the shell in which themotor is housed and through which the shaft projects. The shell when inuse is immersed in a surrounding liquid, and is filled with a dielectricliquid to protect the motor windings. The liquid seal is interposedbetween the external and internal liquids to prevent admixture thereofand consequent reduction of the dielectric strength of the internalliquid. v

The seal which has been found to be most effective for this purposecomprises, generally, a

rotating cup-secured to theshaft and containing a body of mercury orother liquid of relatively high specific gravity; and an apron or bafliesecured to the stationary shell and dipping into the mercury to dividethe surface thereof into two.

long periods of time,

the invention utilizes thepumping action produced by rotating surfaceshaving radial components, to set up within the body of sealing liquidlocal countercurrents in proximity to the surfaces of contact betweenthe sealing liquid and the'internal and external liquids. Of particularimportance is the establishment of a countercurrent adjacent therotating shaft and in proximity to the surface of contact between theseal- I ing liquid and the external liquid, whereby any external liquidtending to move downwardly around the shaft is swept therefrom by thecounter-current and returned to the surface by .the centrifugalseparating action of the heavier sealing liquid.

When a liquid seal of the type referred to is rotated at the high speedscharacteristic of electric motors, the powerful centrifugal forceproduced causes the heavy sealing liquid, which is usually mercury, tobe forced outwardly against ternal liquid into the space normallyoccupied through the seal, even at an infinitesimal rate;

constitutes a serious defect.

It is, therefore, a. principal object of this in- -vention to reduce thepossibility of migration of either internal or external liquid throughthe sealing liquid of a seal interposed between a rotating member and astationary member. In the present invention this object is attained byestablishing a barrier adjacent each surface of contact between thesealing liquid and the internal and external liquids, whereby the latterare prevented from migrating into the sealing liquid to any substantialextent. In this way, a body of substantially pure sealing liquid ismaintained at the juncture of the two portions of the seal.

A- further object of this-invention is to set up adja ent each surfaceof contact a localized circulation within the sealing liquid, thedirection and nature of the circulation being such as to oppose entranceof foreign matter into the mercury beyond the region of suchcirculation.

More specifically, a preferred embodiment of -by the mercury when atrest.

A further object of this invention is to provide a seal wherein thedisplacement of mercury is materially reduced, and wherein the height ofthe surfaces of contact between themercury and the liquids to beisolated is also greatly reduced.

Both of these objects are attained by disposing,

illustrating the conditions therein during rotation.

Referring to the drawings, Fig. 1 shows a preferred form of seal,incorporated in a submersible electric motor, especially adapted for usewith a the accompanying drawings,

' pling member ,|3.

well pump. The motor (not shown) is encased in a fluid-tight shell I, towhich is secured an upper extension housing 2, the shell and housingbeing sealed by a fluid-tight joint 3. A seal mounting bracket 4 isbolted or otherwise detachably secured to the upper end of the housing,and'is sealed thereto by a gasket 5. An adapter 6, mounted above thebracket, supports the motor assembly in axial alinement with a pump (notshown) mounted above the adapter.

The rotor shaft 01' the motor extends into the housing 2 and isoperatively connected by complementary interengaging coupling members l2and Hi to an intermediate shaft H, which for convenience will be termedthe seal shaft. As shown, the driven coupling member I3 is formedintegral with shaft H. The upper end'of the seal shaft is operativelyconnected by coupling members 5 and .I6 to a pump shaft Inasmuch as theshaft arrangement and the mounting of the seal are described more indetail and claimed in our copending application Serial No. 178,741,filed concurrently herewith now Patent No. 2,171,749 issued September 5,1939, they will be only briefly described herein.

The liquid seal, designated generally by reference character 26,consists primarily of the shaft H, a cylindrical shell 2|, and an apronor baille 22. The shell 2| has an inwardly projecting flange 23 formed'on its inner periphery and provided with a machined lower radial face24 which seats on a radial face machined on a shoulder 25 formed at-thejuncture of shaft 4 and con- The shell 2| extends downwardly around thecoupling member with a close sliding fit, and is threadedly engaged by aclamping nut 26 to firmly engage the surfaces 24 and 25 together. Inthis manner the shell 2| is rigid-- 13/ secured in concentric relationto the shaft. A gasket 21.-is confined within a recess between the shelland the coupling member and, when compressed by a gasket ring 28 engagedby the clamping nut 26, forms a fluid-tight joint between these twomembers. The shoulder 25 forms the base of an annular channel defined byWe shell 2| and the shaft H, the channel being devided by the bailie 22into an inner primary zone 3| and an outer secondaryzone 32, the baffleterminating a short distance above the base of thechannei to provide azone 33 communicating with zones 3| and 32.

Disposed within and secured to the upper end of shell 2| is an annularseal mounting member 36, the inner periphery of which is spaced fromshaft l4 a suflicient distance to accommodate the upper cylindricalportion 31 of the apron 22. The member 36 is welded to the shell to forma fluid-tight connection therewith, and rests on an inwardly projectingflange 38 formed on the shell. Radially inwardly opening cavities orpockets 36, forming overflow channels for the mercury, are provided inmember 36. An antifriction bearing 46 rotatably supports the member 36,and hence the shell 2| and shaft l4, in the mounting flange 4.

The cylindrical portion 3'! of the baflle proto the mercury chamber.

trudes through the flange 4 and is sealed thereto by a gasket 43confined within a ring 44, the baffle being secured to flange 4 by a nut45 threaded thereon. The baille extends upwardly around the shaft andterminates within a recess 46formed in the upper seal shaft couplingmember l5, and is spaced from shaft 4 throughout An annular space 56 isprovided between the outer periphery of the upper baflle portion 31 andthe mounting member 36, through which the liquid filling the housing 2and shell I may enter the outer zone 32 of the seal chamber. Thisannular space is constricted at 5| to a very small clearance, theconstriction serving as a throttling means, the purpose of which will beexplained hereinafter. The lower end of passage 56 is flared outwardly,as indicated at 52, for a pur- H in Fig. 4, and the motor shell I andhousing I 2 are filled with a dielectric liquid such as oil, the latterentering the annular space 56 and filling this space and a part of thepockets 36. When the unit is submerged in water, for example, the latterenters the channel 4'! down to the mercury level. Upon starting themotor the rotation of shaft 4 and shell 2| causes the mercury to rotatetherewith, centrifugal action causing the mercury level in the innerzone 3| to drop to the position shown at 55 in Fig. 4, and shifting thelevel in the outer zone to the position shown in Fi 4, wherein 56designates the lowermost portion of the contact surface in the outerzone. The surfaces of contact between the mercury and oil at 56, andbetween the mercury and water at 55, assume substantially verticalpositions, that at 56 being substantially flush with the inner peripheryof the mounting member 36 and that at 55 being substantially verticallybeneath the former, the surfaces 55 and 56 lying ina paraboloid coaxialwith shaft H. The displaced-mercury will overflow into pockets 3! andwill be retai-ned therein during rotation. The downwardly and outwardlyflared portion 52 at the lower extremity of the passage 66 creates apumping ac-- tion exerting pressure downwardly against any emulsion ofmercury and oil which might otherwise rise in passage 56. The minuteglobules of mercury will be separated from the oil and thrown outwardlyagainst the inclined wall 52, where they will be forced downwardly intothe upper overflow chamber. The characteristically high rate ofacceleration of the motor when first energized would throw aconsiderable portion of the mercury up into the pockets 39 and possiblyup through the annular space 56 and into the housing 2, were it not forthe provision of throttling means 5| in the'passage 56. A close runningfit of only a few thousandths of an inch is provided at 6|, serving as adashpot'to check the upward surge of mercury by throttling the pas- Aspreviously stated, when the mechanism is at rest, the level of themercury is preferably above the bottom of the lowermost of the twopockets 39 at substantially the level a-a. when the pump is running,however, the mercury surrounding the shaft I4 moves downwardly to theline. 55, thereby displacing part of the mercury in the exterior zone 32over the flange defining the lower wall of the lowermost pocket 33, intothat pocket. By initially providing an excess of mercury in the spaces3| and 32, and providing for the overflow of the mercury into thepockets 33, a substantially constant supply of mercury in the spaces 3|and 32 is secured when the device is rotating. In order to achieve thisresult, it is merely necessary to maintain the level of the mercury whenthe device is at rest, somewhere above the lower wall of the lowermostpocket 39, thereby eliminating the necessity of accurately gauging theamount of mercury inserted into the device.

An important feature of this invention, constituting a radical departurefrom the design of prior seals, is the location of the seal chamberwholly radially outside the passage 50. This is accomplished in theillustrated embodiment by enlarging the shaft [4 from a point below themercury level to the base of the chamber. As shown, a series of steppedenlargements forming shoulders 66 and 6| increases the inner diameter ofthe seal chamber to exceed that of the member 36. In this way a downwardprojection of the paraboloidal surface assumed by the mercury surfaceswhen rotated, would lie wholly within the enlarged portion of the shaft.

At the rotative speeds employed, the apex of the paraboloid is actuallyseveral feet below the seal, and consequently, within the verticallimits of the seal, the extension of the paraboloidal surface issubstantially vertical, as shown in dotted lines-at 62 in Fig. 4. Sincethe main body of mercury is always disposed outside the aforesaidparaboloidal surface, even when at rest, very little displacement takesplace upon rotation of the mercury-onlythat required to move the surface56 from the level -0 to the position indicated in Fig. 4. As a result,only a relatively small quantity ofvexternal liquid is admitted to thespace normally occupied by mercury when at rest.

As stated previously, an outstanding feature of this invention is theestablishment of a barrier in proximity to each of the surfaces 55 and56, opposing the entrance of water or oil lnto'the mercury to anysubstantial extent. In the present instance, this barrier is formed bythe creation of eddy currents in the mercury, the particles traveling inorbits which are closed in planes extending through the axis of theshaft. These eddy currents are created by utilizing the pumping actionproduced by rotating surfaces having radial components. In the innerprimary zone 3! the rotating element is the shaft H, and the shoulders66 and 6| formed thereon at the points of enlargement of the shaftprovide such radial surfaces. The shoulder 60 produces 'an eddy current,shown by arrows 63, while'shoulder 6| produces a second eddy currentindicated by arrows 64. Enlarging the shaft at the upper portion ofthemercury chamber has the, further advantage of making it possible totaper the shaft downwardly from the shoulders to the base of thechamber, the upwardly flaring conical surface 65 producing a pumpingaction which creates upward flow of mercury along the shaft,

as indicated at 66, in opposition to the aforementioned tendency of thewater to work its way downwardly around the shaft.

The shoulder 66 is so proportioned as to extend radially beyond theinner periphery of the member 36, thus insuring that the lower edge ofthe fluid-contact surface 55 will rest on this shoulder, limiting theheight of this surface of contact between the mercury. and water to a'relatively short distance. The powerful centrifugal separating actionproduced by the rotation of the much heavier mercury at high speedcounteracts any tendency toward emulsiflcation of mercury and water;however, should any minute particles of water be picked up by themercury at the surface of contact, they would be carried outwardly awayfrom the shaft by the eddy current 63 and deflected upwardly by thebaiiie 22, and subsequently squeezed out of the mercury by thecentrifugal separating action. Anywater tending to seep along thesurface of the shaft between the latter and the mercury would likewisebe swept into the eddy current. The eddy currents 64 and 66 constituteadditional safeguards against -migration of oil downwardly through themercury or between the mercury and the outer surfaces of the baiile. Theradial surfaces 16, H, and 12 formed on the member 36 and shell 2|produce a pumping action which creates eddy currents in the mercurysimilar to those indicated by arrows 63 and 64, except that theirdirection is counter to the direction of the latter because of the factthat the radial surfaces are above the eddy currents instead of belowthem. A single continuoussurface from the inner periphery of member 36to the outer wall of the chamber would produce an effective eddycurrent, but breaking up the surface into the series of stepped surfacesI0, II and 12, as shown, has advantages over a single surface. In thearrangement. shown, the mercury moving outwardly along surface-10impinges on the annular surface 13 and is turned back toward the baiile,establishing a closed circulation indicated by arrows 14. Likewise, aseparate eddy current, indicated by arrow 15, is set up by radialsurface Ii and annular surface 16. A third eddy current is alsoestablished between the wall of the chamber and the baffle, as indicatedat i'l. By breaking up a single eddy current into a plurality thereof inthe manner shown, the velocity of the currents, and consequently thelikelihood of inclusion of particles of oil, are reduced. Furthermore, aplurality of separate eddy currents in series is obviously a moreeffective barlighter liquid is forced radially inwardly by thecentrifugal separating action, and, when in contact with a conicalstationary surface, tends to move in the direction of the smallerdiameter, the reverse of .what takes place adjacent a conical rotatingsurface. Thus the eddy currents 66 and I8 are produced in the mercuryspace along- 7 side the lower skirt portion of the baffle, thecirculation being upward along the outer, upwardly converging bafllesurface in the outer zone 32, and downwardly along the inner surface ofthe baflie and upwardly along the upwardly flaring shaft, in the innerzone 3|.

Since the aforementioned conical surfaces have only small radialcomponents, the circulacient time for any particles of lighter liquidinthis area to be forced radially inwardly by the heavier mercury beforethey reach the lower end of the circulation path, and to be carriedupwardly by the rising current of mercury adjacent the inner wall ofeach zone.

By reason of the establishment of eddy current barriers as described, abody of pure mercury is maintained in the lower portion of the sealchamber, in any event, the pure mercury extending at least to the levelindicated at 80. An additional eddycurrent will be created at 8| byreason of the shoulder 25, but this circulation is also of minorimportance since it occurs in pure mercury.

In addition to the improved sealing effect described above, theconstruction shown has other distinct advantages over prior seals. Thelengths of the liquid to liquid contacting surfaces have been verymaterially reduced, resulting in a proportionate reduction in thetendency to emulsification of liquids at the contact surfaces.

The provision of short, vertical, liquid to liquid contact surfaces hasthe further advantage of eliminating rotative speed as a variable factoraffecting the nature of the seal. Throughout the full range of practicalspeeds, the contact surfaces will remain substantially fixed since theyare confined to very short portions of the upper region of theparaboloid. ,Reference to Fig. 4, and to line H thereon will also showthe relatively slight change in the level of the contacting surfaceswhen rotating as compared with the stationary level; the amount of waterin the seal when rotating is only slightly greater than when stationary.By providing pockets 3!] of relatively large capacity, even verymaterial variations in the amount of mercury provided will have littleeffect on the standing level of the mercury, as indicated at H in Fig.4; also, by reason of the small volume of the annular space 41 betweenthe shaft and the upper baflle portion 31, a substantial change in thelevel of the surface of contact between the water and mercury results inthe displacement of only a relatively small amount of mercury. Also, theamount of mercury employed in the seal is only a small fraction of thatused heretofore, and, because of the slight displacement of mercuryresulting from rotation, substantially the entire .amount is' utilizedrather than being displaced out of the direct line of communicationbetween the two contacting surfaces, as in prior seals. It will beobserved also that-the minimum diameter of'the enlarged portion of theshaft M is greater than the inner diameter of the mounting member 36,thus precluding the possibility of the contact surface between themercury and water being projected downwardly below the shoulders 60 or 6l While the novel features of this invention have been illustrated anddescribed as applied to a liquid seal in which the mercury chamber issecured to and rotated with the rotating shaft, and the baiiie issecured to the stationary housing, it is obvious that this is only oneof many applications of the underlying principles. For instance,

.in combination with a slowly rotating shaft, the

chamber may be stationary and the baiiie may be secured to the rotatingshaft, in which case the baillewould be provided with surfaces havingradial components to produce a pumping action. It is also within thescope of this invention to apply the novel features thereof to a liquidseal between a'stationary shaft and a rotatable housing.. For highspeeds, the seal chamber would be attached to the rotatable housing andthe baifle attached to the shaft, while for low speeds the reversearrangement would be satisfactory. An example of the first-mentionedalternative form of seal to which the novel features may be applied, isshown in Fig. 5 of the patent to Earl Mendenhalland Junius B. Van Horn,No. 1,- 879,626.

We claim:

1. A liquid seal for use between a rotating shaft and a stationarymember, comprising in combination: an enlargement on said shaftterminating at its upper end in an upwardly facing shoulder continuouswith and extending outwardly from said shaft; a shell secured at itslowerend to said enlargement and extending up-.

wardly in spaced coaxial relation thereto, the upper portion of saidshell above said enlargement being constricted to form a neck of smallerdi ameter than the shaft enlargement; and an annular baffle secured tosaid stationary member and extending downwardly into the space betweensaid shaft and said shell to a point below said' an annular chamber inthe lower portion thereof containing a body of sealing liquid, the upperportion of said receptacle being reduced internally to form a neck ofsmaller diameter than the diameter of the major portion of the innersurface of said chamber; and a baflie secured to the other of saidmembers and having a lower skirt portion extending into said sealingliquid and an upper reduced portion extending through said neck.

4. A liquid seal for sealing the juncture of a stationary member and arotatable shaft com.- prising, in combination: a receptacle secured tosaid shaft and having walls defining an upper reduced annular neckpassage and a lower annular chamber containing a body of sealing liquid,an annular baflle secured to said stationary member, said baiile havinga skirt extending into said sealing liquid and an upper reduced neckdividing the said neck passage into two relatively narrow concentricannular channels; the inner wall of said receptacle having an upwardlyfacingsurface located a substantial distance above the lower extremityof the baffle skirt and extending transversely beneath the outer of saidchannels. said sealing liquid having a surface terminating at apredetermined location on said upwardly facing surface during rotation;and a constriction in said outer channel providing a throttling passageto check upward surge of sealing liquid through said outer channelduring acceleration, whereby said sealing liquid surface graduallyapproaches and comes to rest at said overflow chamber in said receptaclepositioned above and communicating with said annular chamber, saidsealing liquid partially filling said overflow chamber at all times.

6. A liquid seal comprising in combination an annular rotatablereceptacle containing a sealing liquid, an annular stationary bafliedepending downwardly into said sealing liquid and dividing the surfacethereof into a plurality of separated surfaces adapted to be contactedby fluids to be isolated by the seal, in which at least a portion of theinner surface of said bafiie extending into said sealing liquidconverges downwardly and inwardly.

'7. A liquid seal comprising in combination an annular rotatablereceptacle containing a sealing liquid, an annular stationary bafiiedepending downwardly into said sealing liquid and dividing the surfacethereof into apluralityof separated surfaces adapted to be contacted byfluids to be isolated by the seal, in which at least a substantialportion of the inner surface of said bafile converges downwardly andinwardly and at least a substantial portion of the outer surface of saidbaflle within said liquid converges inwardly and upwardly.

8. A liquid seal for sealing the juncture of a stationary member and arotatable member, rotatable about a vertical axis, comprising areceptacle secured to the rotatable member and having walls definingan-annular chamber closed 1 portion whereby said baiile conformsgenerally to the shape of said chamber and is spaced from the wallsthereof, said baflie dividing the sealing liquid into two bodies havingseparate free surfaces lying in the intermediate portion of saidchamber, said receptacle having radial surfaces on its inner and outerwalls adjacent said two sealing liquid surfaces for setting up closedcirculation of said sealing liquid in radial planes adjacent said liqhidsurfaces.

9. A liquid seal as described in claim 1, in which said bafileextendsvoutwardly and downwardly in close proximity to and above saidshoulder whereby the area of free surface of said sealing liquid betweensaid enlargement and said baflie, when the shaft is rotating, is small.

10. A liquid seal as described in claim 1, in which said bailie extendsoutwardly and downwarly in close proximity to and'above said shoulderwhereby the area of free surface of said sealing liquid between saidenlargement and battle, when said shaft is rotating, is small, and inwhich said baflie extends upwardly in close proximity to said shaftabove said outwardly and downwardly extending portion, whereby thevolume of external fluid within the seal structure is reduced.

11. A liquid seal as described in claim 1, in which said shell isenlarged above said neck portion thereof to provide an overflow chamberand said baflle extends in close proximity to said shaft above the upperlevel of said sealing liquid, the volume of said overflow chamber beinglarge in comparison with the volumeof the clearance between said shaftand the upper portion of said baffle.

12. A liquid sealas described in claim 1, in which the upper end of saidenlargement on said shaft is stepped to provide a plurality of upwardlyfacing shoulders, including said first mentioned shoulder,longitudinally. and radially spaced from each other.

13. A liquid seal comprising a rotatable receptacle defining an annularchamber containing a sealing liquid and a stationary annular bafliedepending downwardly into said sealing liquid, in which the wall of saidreceptacle exterior of said bafiie is shaped to define a plurality ofdownwardly facing shoulders in stepped relation to each other positionedadjacent the free surface of said sealing liquid when the receptacle isrotating.

. ALADAR HOLLANDER.

VAINO A. HOOVER.

